Hub mounted control



P 1953 J. E. ANDERSON 2,653,668

HUB MOUNTED CONTROL Filed March 30, 1949 5 Sheets-Sheet l 1/9 22 0 rne y Sept. 29, 1953 J. E. ANDERSON HUB MOUNTED CONTROL Filed March 50. 1949 5 Sheets-Sheet 2 REVZRS/Nf 5/ 7 SOLE/VOID Iii/71822120 JoFeuE editor-e5;

Sept. 29, 1953 J. E. ANDERSON HUB MOUNTED CONTROL 5 Sheets-Sheet 4 Filed March 50, 1949 A96 ll/X. Mara? .SCJVEN E PUMP Sept. 29, 1953 J. E. ANDERSON HUB MOUNTED CONTROL 5 Sheets-Sheet 5 led March 30, 1949 nuumnnIE Int/en for Joiaulfi flame? r5070 .9 J/ww;

patented Sept. 29,

BUB MQU F H' John E. Anderson, Portland, Conn assignor to rUnit'ed; Aircraft \icorporatiomsrEast vliartford Conn; a corporation of Delaware sin ster furtherobject iaa propeller-control unit having a propeller-carried -non-rotating COI-ltlOl system; including a 1 iiuirl'*sup-ply independentof the engine lubricating system, for upplying pres sure fiuid torotating pr'o'peller' pitch changing ch'anism.

still further object is a. propeller-control unit havinga propel-ler carried nch-rotating control system including means-for controlling the same to 'efiecteonst'ant speed contrc'vl; feathering and eversheig'x 411.2. I. i if? :1. 1 3 3;; A-still further object is a non-rotating control in a propeller-control uni-t with provisionefifor LI. it v": L115 imlei still-' 'fu rther object is to provide a self contained propeller-control unit which" may be compl'etely assembled hefore b'ein'g- 'secured onthe 't fopeller smartshe man delivers en iron the control unit-"tb-the propeller but does ndtr u e specialorrriodifichpropeller shaft:

A still further object is an improved prop hydraul-ic'control'sy'stemi 1 Other objects-and-advantages will be apparent froizfthe' specificationand-claims;"and fromthe accompanying drawings which" illustrate what is new considered to beth'e preferre 'emho'di- 6 mn't'of the invention) 1 5 *Figure l isaside view, with one blade removed, or the propeller-control unit or this app a Q Figure f2 "is 'a schematic side 1 v ew showingthe eller hydraulic control system and thef 4 :1

"e'chanismi i j Figure 3 is a schematic diagram of the electrical and hydraulic'circuits ofth'e'control. i

"Figure *'is apers'pe'ctiveview; with portions broken away, 0f the 'COh'trOl unit, removes the "propeller; looking at the "controfiinit thepropell'er side. "{Figure *5 is-'-a somewhat schematic diagram showing, in an end view; the hydrauliccontrol circuit and-the arrangement'ol pa rts.

taken on lineseer Figure 4 showing "the centrol'm'ounted on the propeller hub I Frureeis aseotion through the control unit "[l igure fisa'd'etailed sectional view taken on 'iith so, 194si, memos lfi Claims. (o1. m iisiri) required that the propeller controlsbe -bolted to 'the engine noseandthe propeller placedseparately' on the propeller shaft which requires considerable adjustment when the propeller -is assembled onthe propeller shaft and connected with the' controlsr' Other such attempts have required 'that the controls and oil reservoir rotate with the pr'opellers Applicant has invented a hydraulically controlled: propeller: in which the "oil reservoir and" controls 1 are stationary and are rotatablysupportedon bearings on the propeller and the oilconnections between the controlsand the'propeller'are made-through the propeller hub someone modificationof the propeller shaftis reqmred -w provide the necessary oil passages.

SEW-this construction applicant is able to utilize "oil of a'riy desired"characteristic for-operating the propeller-and no'longerhas to rely on the lubricating oil of th'eengine as propeller operatingoil.

such a propeller-constitutes a unitary structure which-may be' 'completelyadjusted on the bench prior to asser'nblyon the propeller shaft and then assembledon the propeller shaft without furtheradjustment; I The hydraulic control systemremainsstationaryand is electrically controlle'dfrom a convenient control station 'to provi'defiinadditiontoconstant speed control, means for feathering; unfeathering, reversing, andunr'eversingthe' propeller. This is all accomplished in a'unitary x'nechan'isminwhich the oil'reservoir 'andall'" the control elements are arrangedin'a In'the drawings which illustrate a mechanical construction which' is'now considered-"the prefer-red form ofthe invention,--the-control unit is "indicated "generally at Band is shownas rotata- -'bly" 's'u-pported on bearings onthe propeller ---unit,

"generally --'indicated= at l2; l The control unit I 0 includes a"- bearing sleeve I I which is telescoped with and supported on an axial projection I6 on the hub I8 of the propeller I2. The sleeve I4 is secured in position on the hub and held against axial or rotational movement thereon by notched rings 26 and 22. Sleeve I4 is provided adjacent the propeller hub with upstanding lugs 24. Ring 22 is provided with depending lugs 26. The ring 22 has a diameter at the inner side of the depending lugs 25 substantially equal to the diameter of the outside of sleeve 14 for a length substantially equal to the open space between the upstanding lug 24 so that ring 22 with its depending lugs 26 may be assembled onto sleeve I4 and rotated so as to engage the rear of upstanding lugs 24.

Ring 26 has depending lugs 28 and an inside diameter equal to the outside diameter of sleeve I4 so that ring 28 may be placed over sleeve I4 and in the plane of upstanding lugs 24.

As shown in Figs. 4 and 6, ring 20 may be fastened by means of cap screws 30 to the hub I8. Rings 20 and 22 may then be secured together by means of cap screws 32 threaded into ring 22. When thus assembled, ring 22 will axially position sleeve I4 and the control unit relative to the propeller hub and ring 20 will prevent relative rotational movement of the hub I8 and the sleeve I4. Relative rotational movement of sleeve I4 and hub I8 would be prevented by contact of the lugs 24 and 28.

The propeller may be of any type utilizing hydraulic fluid for pitch changing and preferably having the propeller pitch changing motor carried by and rotating with the propeller. In the preferred form, the pitch changing motor comprises a piston mounted in a cylinder 34 and by means of cam slots 36 and cam rollers, not shown, turns a connecting gear 38 geared to the propeller blades 40 to thereby change the propeller blade pitch. Oil may be selectively directed to either side of the pitch changing mechanism by means of conduits 42 and 44. The propeller is secured to a propeller or engine shaft 46 supported in the usual manner by bearings in the engine or engine nose. For further details of these propeller constructions, reference may be made to Patent No. 2,477,868 of George W. Forman, filed April 17, 1946 and issued August 2, 1949. Reference may also be made to Patent No. 2,371,873 of Erle Martin, issued March 20, 1945, for a further disclosure of a suitable type of propeller for use with the control of this application. As this type of propeller is now well known, further detailed description thereof is believed to be unnecessary.

Hydraulic fluid is led from the control mechanism to the propeller through the conduits 42 and 44 in the propeller hub. Conduit 42 leading into the hub outside of propeller shaft 46 and through suitable connections such as shown in Patent No. 2,477,868, is led to the forward side of piston 32. Fluid may also be led through conduit 44 in the hub to the interior of the propeller hub and the space to the rear or inboard side of piston 32. Suitable means such as a gasket 48 prevents flow of oil inboard along the propeller shaft, the propeller surrounding the outboard end of the propeller shaft closes the outboard end against the loss of oil in the outboard direction. Oil from the control mechanism is directed into a groove 50 in the outer surface sleeve I4 which is connected by suitable passages 52 with a groove 54 on the inside of sleeve I4, which when assembled on hub projection I6, is in hydraulic communication with conduit 42. Oil may also be led from the control unit into groove 56 in the exterior of bearing sleeve I4 which is connected by suitable passages 58 with groove 60 formed in the interior of bearing sleeve I4. Groove 60, when assembled on the hub projection I6, is in hydraulic communication with the conduit 44. A groove 62 located between groove 54 and 60 is not utilized for any special function in the structure shown in this application. A series of O ring seals 64, 66, 68 and I0, located between the sleeve I4 and hub projection I6, define these grooves and serve to prevent oil leakage therefrom. The threaded portion 72 located at the inboard interior of sleeve I4 is provided to assist in removing the sleeve and the control unit from its assembled position on the hub projection l6.

The control unit I0 comprises a main casting I4 which supports all of the various control elements including the governor valve indicated generally at I6, the scavenge pump, indicated generally at 78, main pump and its connections, indicated generally at 80, the auxiliary pump and motor, indicated generally at 82, the various valves and their controls, to which reference will be made hereinafter, and the oil reservoir, indicated generally at 84. The various control elements are preferably separate units bolted or otherwise removably seured to the main casting. A bearing sleeve 86 is secured in main casting I4 and serves to rotatably support the entire control system on the bearing sleeve I4 which is secured as previously described on the hub projection I6. Bearing sleeve 86 is provided with a bearing metal such as babbitt on its inner diameter and inboard face which provides a bearing surface cooperating with the outer surface of bearing sleeve I4 to provide a suitable running joint and oil seal between the stationary control unit and the rotating propeller unit. As shown in Figs. 6 and 7 upstanding flange 222 of sleeve I 4 projects between one end of bearing sleeve 86 and a thrust plate 81. Suitable fastening means such as screws, not shown, secure both the thrust plate 81 and sleeve 86 to main control casing 74. Flange I22 being positioned between bearing sleeve 66 and thrust plate 81 positions the entire control mechanism with respect to sleeve I4. Sleeve I4, as previously described, being positioned with respect to hub I8, therefore serves to locate the control mechanism with respect to the propeller and maintain them in assembled relation.

Four grooves 88, 96, 92, and 94 are provided in the outer surface of bearing sleeve 66 and, like the grooves in the interior of sleeve I4, are prevented from leaking by means of suitable 0 ring gaskets. Suitable passages lead from groove 94 through sleeve 86 to groove 56 in sleeve I4 and other passages lead from groove 88 through sleeve 86 to groove 50 in sleeve I 4. Groove 90 is not utilized for any special function in the structure shown in this application and the passages leading from groove 92 to groove 62 are not utilized for any special function. Suitable passages led from grooves 88 and 94 to the governor valve which being thus connected with the propeller pitch changing mechanism controls the flow of oil to and from the pitch changing mechanism. Groove 92 is connected with the output of the main pump. Various passages in the main casting connect with groove 92 to deliver the output of the main pump to the low pressure relief valve, indicated generally at 96, high pressure relief valve, indicated generally at 98, and to the governor valve I00. A passage I02 connects an auxiliary pump I04, driven by auxiliary motor I66 with passage 82. As will be explained later, this auxiliary pump and motor. are used toprovide pressure. fluid when the propeller is not rotating and. the main. pumpis consequently idle.

A main sump orreservoir is formed atoneside of the main casting I4 of thecontrolunit which is the lower side when thercontrol unitis inits normalupright position, by means of acurved, trough-like cover I08 secured .to thel WQr portion of main casting I4 by cap screws LI!) and sealed by suitable. gaskets I;I.-2. Bolts I-Ij; are utilized to prevent expansion of thecoverbythe pressure usually carried in the, reservoir. The main pump 80 is enclosedbythe cover ID B and comprises a gear pump. .ILI Ii driven through gear :l.-I8 by agear I formed on an upstandingilange I22 on the inboardside of sleevel l secured torotate with the propeller. Bump IIB has an inlet I2 4. located near thebottom otthereservoir. Ifhis inlet, however, is spaced fromthe bottom ofthe reservoir agreater distancethan inlet -I 2 -6.1ead

ing toauxiliary pump I04 so that in the event of failure ofthe propeller to change. pitch due to lack of..oil it may stillbe possible to feather the propeller by means or" the auxiliarymotor which can still pumpoil ifthelack of oil isjcausedby the level falling justbelow theinletto themain pump.

Provision is also made for supplyi 0111.20 the main pump during inverted flight. A gravityactuated ring I28, slideableina cylinder I38 islnormally held by gravityin the position shown in Figs. 4 and-5 so as to close orifice I32 and leave inlet I24 unobstructed. Whenthe vcontrolunit is inverted as in invertedflight, ring I28 will be moved under the influence of g avityto a position closer to the gear pumpal IIito thereby closeinlet I24 and open orifice.- l32 .which is connected by a conduit to an inlet I34 located near the top of the. oil reservoir which, of course, would be the bottom of the oilreservoir in inverted flight. It should be noted that both the oil ,andring I28 are positioned by the same force, normally gravity, so that other forces such .asacceleration which might displace the oil wouldalso displace the ring. As stated above, oil from main pump I I6 is led to passage 92 and thence to;the governorvalve 1 I00 from where it is. directed in the usual manner by the governor tolthe proper sideor" ;the pitch changing motor to maintain constant propeller speed by varying the. propeller pitch. The gov- 0 ernor is driven from gear. I20 by gear; I36 and a pair of bevel gears asshown in Fig. 4. The governor comprises the usual flyweights I! opposed 'by-a speeder spring whose tension may be ad- :justed in a wellknownmanner by an electric motor, not shown, which in turn may be connected to controls from the pilots cockpit. Pres- I 54 leading to a piston I on thetop of the governor valve I 00 thereby forcing the pilot valve down todirect pressure fluid from groove .92 into groove 94 and thenceto the pitchlreducing-side of the piston 32 in the pitch changing motor.

Pressure oil is also led from .the passage. .to

gs W111 collectindrainage areas at and 1 12 which are sealed by suitable gaskets; twofof' whichifaffe lip type gaskets; I7 I, I13 forminga runningfseal the. r m h o 1 13 12 45 o e i fv veflfi whic is urged i oclosed posit on by s i .8 The. r l e settin 9i r ie WW? -35 ifi6fh1e11r deter nedb he C c of Spring emma e in reasedib eadin i nd ie s he backsid r plunger ts? This is accempusnee bye Shuttle valve I (it), one sideof which con; nected wit the. eve s ns l i 4. a e th upper sideof piston I 5. 5 on the governor valve ,IIIP. and the oth er side of. which is connected'with the groove E18,8 leading tqthe pitch increasing side fo'f than .ch..cl. ane nemqior- H m Ii sv' h v isins v v n rmed o wh n v i ir fluid is bein :l d in h p te mf ine i e of he, pi ch p un in .in tq th acity ldfithe relief valve fit is increased to thereby increasethe pressure outputof the, main pump. shuttle valv e ttn. moves unde t e. pr domina t r fa tins thereon to connect that predominant pressure Withthe ea Q tne plun e .56.

Under certain conditions which will v.bedescribed later, it maybe desirable to increase the pre sure l e t th underside 919 35 1??? over that which is produced by the pumps when their pressure is determined by the normal settins f ,reli fvalv efi- In ord r br d'e-ie h s con i gen y a shutt e v e I5 m l ce nected into line. I59 leading toshuttlevalve'ilin, Shuttlevalve 1 5] is connected betvveen the line .1 leading-from the upptr si deof piston I55 and/the line leading from the lower sideof piston I52 so that when pressure is applied to the lower side of piston I52 shuttle valve I5] ,willjbe operated. to

direct pressure fluid-from piston I52 to-line ll to move shuttle valve; I50. and apply that pressure to ac p pl g r .56. of re va v firessure applied to the upper side of pisto'n I55 will move shuttle valve I5'I and connect piston.l5;5 with line-I59. to back up plunger I56 in the same manner as described above without reference to h tuevalv I51. -.This is an ,added'f'eature that may b qu red. only 011 $0 s ella qnsend is, therefore, shown only in Figures 3 and 4. This shuttle valve I51 being omitted from Figures and 5 tor the purpose of simplicity.

.Gmqve Q is a s con e e wi a high. e

h n t rou h sb 51 Gears I62 of scavenge pump 18 are driven through gear I54 by gear I20 and serve'to remove oil that may collect in the drainage area I66 and force it into the reservoir I68 tokeep thedrairiage area free from an 'accu mulationof oil and maintain. reservoir I Q8 under a'press'ure determined by the reservoir relief valve indicatedgenerally at I10. Pump 18 may pump'bothoil airl'to maintain the reservoir pressure.

on leakagefrom theiends of the bearing sleeve between the propeller and control .iThese gaskets If! I, I13 are arranged so that leak inward past. them if the. outside pressure isthe greater, thus tending to reduce oil leakage. Drainage area I12 is connected with drainage area I66 by holes, not shown, in the main casting 14. These drainage areas are maintained under atmospheric pressure by. being vented to atmosa spring pressed plunger I 14, normally'closinfgl'a port I16 in a cylindrical bore I18. The underside of plunger I14 is subjected to the pressure maintained in reservoir I68, being connected therewith through a passage I80 and drilled. holes shown diagrammatically at I82. When the pressure in the reservoir I68 is sufiicient to lift plunger I14 the sump will discharge through port I16 to the area surrounding gear I20 and upstanding flange I22 and thus be conducted around the inside of thrust plate 81 lubricating the gears on the way and down back to the drainage area I66. Drainage area I66 is continuously connected with the outside atmosphere through a passage I84 and ports in the plunger I74 and its casing. The drilled passages I82 connect, as shown in Figure 5, with the upper portion of the sump so that in the normal upright position the relief valve serves to vent excess air from the reservoir to the drainage area and as passage I84 is at the top of the drainage area air is vented from the drainage area to the outside atmosphere.

The main casting I4 has projections I86 extending from one side thereof and forming a slot between them. A lug I83 fixed on engine nose I90 extends to a position between said projections and acts to prevent rotation of the control unit with the propeller While permitting it to move axially and radially with the propeller.

In normal constant speed operation the governor 16 operating valve 08 controls the flow of oil through passages 42, 88, ts and 94 to maintain constant propeller speed by varying the propeller pitch. Shuttle valve is maintained in the position shown in Figure 3 to apply pressure back of relief valve plunger 255 whenever pressure oil is introduced to the pitch increasing side of the pitch changing motor, scavenging pump I62 serving to keep drainage area free from the accumulation of oil and to maintain a predetermined pressure in reservoir I68.

When it is desired to feather the propeller, feather button I92 in the control. compartment of the airplane is pushed to close contacts I94, I96, I98, 200 to thereby energize holding coil 202,

feathering solenoid 204 and auxiliary pump motor continue to supply fluid after the main pump has ceased operation due to stopping of the propeller. Holding coil 202 is in series with a cutout switch 206 which is actuated by the pressure fluid changing the propeller pitch. Opening of feathering valve I48 allows pressure fluid from grooves 92 and passage I44 to enter conduit I50 and act on the underside of piston I52 to lift governor valve I60 which will direct fluid from the groove 92 to groove 88 and the pitch increasing side of the pitch changing motor. Pressure oil in groove 88 will move shuttle valve I60 to the position shown in Figure 3 to put pressure oil back of plunger I56 of relief valve 96 and will move shuttle valve 208 to the position shown in Figure 3 to thereby connect the pressure cut-out switch with the pitch increasing side of the pitch changing motor. When the pitch changing motor has reached its limit of movement determined by stops, not shown, the pressure at the pitch increasing side of the pitch changing motor will increase creating a pressure surge which will open the pressure cut-out switch releasing the holding coil 202 and permitting springs 300 to return the feather button I92 to its off position as shown in Figure 3.

In the event that shuttle valve I51 is utilized pressure fluid acting on the underside of piston I52 will move shuttle valve I51 to direct fluid into line I59, move shuttle valve I60 so as to conduct pressure fluid to the back side of plunger I56. This will increase the pressure output of both the main pump and the auxiliary pump to thereby insure sufficient pressure to lift the governor valve I00 against the action of the speeder spring. After valve I00 has been lifted then the predominate pressure in line 88 or I59 will be the pressure which will move the shuttle valve I60 and back up plunger I58.

To unfeather the propeller from its non-rotating feathered position button I92 is pulled to the left as viewed in Figure 3 closing contacts 302, 304, 306 and 308 to thereby energize holding coil SW and consequently auxiliary pump motor 82 and reversing solenoid 3I2 thus opening reversing valve I48. Operation of auxiliary pump motor 82 will supply auxiliary fluid in the same manner as described for feathering, except that it must supply all the fluid at the beginning of the operation as the main pump II6 then does not operate and it will assist the main pump after the propeller starts to rotate. Opening of reversing valve I48 will allow pressure fluid from groove 92 and passage I44 to enter passage I54 and act on the upper surface of piston I55 to thereby force the governor valve I00 down and admit pressure fluid from groove 92 to 94 and hence to the pitch decreasing side of the pitch changing motor. Pressure fluid in passage I54 will move shuttle valve I60 to apply pressure fluid back of plunger I56 of relief valve 98 to thereby increase the available pressure. Pressure in groove 94 will move shuttle valve 208 to the right as viewed in Figure 3 thereby connecting the pitch decreasing side of the pitch changing motor with the pressure cut-out switch 206. The pressure cut-out switch, however, is not utilized to stop the unfeathering operation as this is accomplished by electrical contacts on the propeller blade shank. When the propeller blade has reached a predetermined position in its pitch reducing movement the current in holding coil 3I0 is broken by an insulating segment 3I4 thus releasing holding coil 3l0 allowing spring 3I6 to return switch 3I8 to an off or neutral position thus breaking the current to reversing solenoid 3I2 and auxiliary motor 82. The plunger which cooperates with holding coil 202 is so far out of the holding coil when button I92 is in unfeather position that holding coil 202 has no effect. Button I 92 is held out manually for unreversing and may be released by any time after the propeller starts windmilling. If, however, it is not released by the time the propeller has reduced its pitch well into the operating range the reversing solenoid and the auxiliary motor will he deenergized by the breaking of the circuit of the holding coil 3 I0 by insulating segment 3I4 at which time the governor will take over control. As in the feathering operation the switch is returned to its neutral position by springs 388 after it is released. Reference may be had to application Serial No. 32,244 of Martin and McCarthy, filed June 10, 1948, for a more complete description of the construction and operation of the insulating and conducting segments on the blade I8. It will be suflicient to state here that by means of a brush, insulated from, and held in fixed position on the propeller hub an electric circuit may be completed by being conducted to ground through conducting segments 328 and 330 and the propeller blade and hub. The brush and segments are arranged so that the brush will be approxi mately at the position indicated by F when the propeller is feathered at the position indicated by L. P'. when the propeller is at its low pitch stops and at B. when the .propeller is in its reversed pitch position. It will thus be apparent that even if switch knob [.92 is held in the unfeather position until conducting segment 320 contacts the brush, the circuit will again be broken by insulating segment 332 before the propelled reaches its low pitch stop. .T is will prevent the propeller from going into reverse pitch while .unfeathering because the pressure level maintained by relief valve es alone, when not backed up by pressure from reversing valve I48, is not suflicient to overcome the low pitch stops.

In order to reverse the propeller pitch switeh 320 is first closed and then reverse-unreverse switch 322 is moved into the reverse position which is the lower position as viewedin Figure 3. Closing of these switches will energize reversing solenoid 312 and holding coils-324. and326. Energizing holding coil 324 will close switch 334 and will close switch338 which will in effect short circuit switch 320 so as tomaintain holding coil 324, 325 energized independent of the position of switch 320. The closing of switch 336 has no immediate effect, but prepares the circuit for unreversing which will be described later. After passing through switches 320, 322 and holding coils 324, 326 the current passes through switch 340 to ground. Switch 340 is normally held closed by spring 342. Energizing the reversing solenoid 3l2 will produce the same hydraulic action as in unfeathering except-that the auxiliary motor is not energized for reversing as thepropeller is beingcontinuously engine driven the main pump will supply all of the fluid necessary for pitch changing. As'in unfeathering governor valve I is forced down so as to connect groove 92 with groove 94 anddirect fluid to the pitch reducing side of the pitch changing motor. It is to be understood that-as is usual in this double acting type of control, each time pressure fluid is conducted to one-side of I the pitch changing motor the opposite side, ofthe motor is connected to drain orthe reservoir to permit fluid to flow from one side of the motor as it is introduced to the other-side. Switches 320 and 322 remain in theclosecl position just described as long as it is desired to have the propeller remain in the reversed pitch position and the propeller is maintained in that position by the fluid from the main pump being continuously directed to the pitch reducingsideof the pitch changing motor thereby forcing the. propeller against the reverse pitch or pitch limiting stops not shown.

To unreverse the propeller andbring it back into the constant speed range, switch 322 is first changed from its reversed to its unreversed position, the position shown in Figure .3, which will deenergize solenoid 312 and close valve I48. .In the unreversed position of switch 322 the current will. be conducted through switch 336which is still maintained closed by holding coil 324 and will energize feathering solenoid or increase pitch solenoid 2534. Switch 320 is then opened, but :as

it is short circuited by switch 338', it has no. im-

creased pitch position.

mediate effect. Placing switch 322 in the unreverse position will also close a circuit to prepare holding coil 344 for action when the circuit is completed through contact 330. Energizing increase pitch solenoid 204 will cause actuation of the governor valve I00 in the same manner as was described in the feathering operation except that the auxiliary pump is not used for unreversing. The governor valve I00 is moved to connect groove 92 with groove 88 andapply pressure fluid to the pitch increasing side of the pitch changing. motor and thus move the blades I8 from. reverse pitch through zero pitch to in- After the blade pitch has been increased to a pitch somewhat above the pitch defined by the low pitch stops, brush 345 will make contact with conducting segment 333, which will energize holding coil 344 to thereby open switch .340. Opening switch 340 will break the ground connection of holding coils 324 and 325 thus deenergizing them. Springs 348 and 350 will now openswitches 334 and 338 and deenergize increase pitch solenoid 204, closing valve I45 and thus returning the governor valve 1.00 .to governor control.

From the above description it will be apparent that applicant has invented a unitary self-contained hydraulically actuated propeller construction which may be assembled on or removed from a standard propeller shaft as a unit and which requires no modification of thepropeller shaft or of the engine in order to accommodate the propeller. The lug 1 88 being the only element attached to the engine may be a separate piece secured by bolts to the engine nose. 'The increase and decrease pitch solenoids and the pressure cutfrom theswitches atthe control station in the airplane may be made to housing 352, the electric controlsforthegovernor Ill, and the auX- iliary motor 82 by means of separable electrical plug connections or anyother suitable type of connection shown generally at 354 and 356. ,These plug-in connections 354, 356 and ground connections 358, are the only propeller control connections that are necessary in removing one propeller and assembling another on the propeller shaft. The propeller contains its own oil supply and ,all of its own .oil conduits and connections.

The propeller has been described in connection witha pressure cut-out switch 206 but if desired a suitable timing mechanism may be substituted for the cut-out switch which mechanism instead of operation .on a pressure. surge, will operate to disconnect ,theauxiliary motor after a predetermined elapsed'time.

.It is vto .be.-.understoo.d, that the invention is not limited .to the specific embodiment herein illustrated and described, but, may be .used in other ways without departure from its spirit as defined by the following claims.

I claim: .1. zApropellerv comprising a hub, .bladesmounted in. ,saidhub for pitch changing movement,

hydraulic .pitch changing mechanism operatively connected ,with said blades and carried by said hub, control mechanism for said pitch chang ing .mechanism comprising a housing rotatably .mounted onsaid hub, and meansfor restraining said housing against rotation with said hub, said ..h0uSil1g includingan oil reservoir, a speed govpump supported by said stationary housing for supplying oil from said reservoir to said hub when the propeller is not rotating, means restraining said housing against axial movement relative to said hub, the rotatable mounting of said housing on said hub including a plurality of fluid passages connecting said governor valve with said pitch changing mechanism.

2. A propeller-control unit adapted for assembly on a propeller shaft as a unit comprising a hub having a shaft connecting portion, pitch changing mechanism carried by said hub for rotation therewith, a control unit rotatably mounted on said hub, means for holding said control unit against rotation, said control unit comprising an oil reservoir, a governor carried by said control unit and means connecting said hub and said control unit and energized by relative rotation of said hub and control unit for operating said governor and supplying fluid under pressure to said governor, and conduits connecting said non-rotating governor with said rotating pitch changing means.

3. In combination, a propeller having a hub and an hydraulically operated pitch changing mechanism rotatable with the propeller, a nonrotating hydraulic reservoir, control mechanism supported on said reservoir, rotatable bearing means supporting said non-rotatin reservoir and said control mechanism on said hub, means restraining said reservoir against rotation, said bearing means including transfer bearings directing fluid from said control mechanism to said pitch changing mechanism.

4. In a unitary propeller-control unit, a propeller including a hub, blades mounted for pitch changing movement in said hub and hydraulic pitch changing mechanism carried by said hub and connected with said blades, said hub having an axial projection with conduits therein leading to said pitch changing mechanism, a stationary control unit comprising a housing, control mechanism, a reservoir and means for supplying fluid under pressure to said control mechanism, and bearing means rotatably supporting said control unit on said projection, said control unit having conduits leading from said control mechanism and connecting with the conduits in said projection.

5. In combination a propeller hub having blades rotatably mounted therein and carrying pitch changing mechanism, an axial projection on said hub, bearingmeans supported on said projection, a separate control unit supported on said bearing means, means for restraining said unit against rotation with said hub, said rotating projection and said non-rotating unit having mating conduits for conducting fluid from said nonrotating control unit to said rotating pitch changing mechanism.

6. A hydraulic control unit for a controllable pitch propeller having a hub, said unit comprising bearing means rotatably supporting said unit on said hub, means for restraining said unit against rotation with said hub, a liquid reservoir carried by said unit, pumps carried by said unit and actuated by relative rotation of said hub and said unit for withdrawing liquid from said reservoir and providing liquid under pressure, a governor carried by said unit and actuated by relative rotation of said hub and said unit, a governor valve, means directing said liquid under pressure to said valve, and from said valve to said propeller hub.

'7. A hydraulic control unit for a controllable pitch propeller having a hub, said unit comprising bearing means rotatably supporting said unit on said hub, means for restraining said unit against rotation with said hub, a liquid reservoir, a pump carried by said unit and actuated by relative rotation of said hub and said unit for withdrawing liquid from said reservoir and providing liquid under pressure, a governor carried by said unit and actuated by relative rotation of said hub and said unit, a governor valve, means directing said liquid under pressure from said pump to said valve, and from said valve to said propeller hub, said pump having an intake adjacent the bottom of said reservoir in normal upright position, a gravity actuated valve automatically closing said intake and opening another intake at the opposite side of said reservoir when the forces acting on said valve are reversed.

8. In a propeller having a hydraulically actuated propeller-carried, separate, removable, hydraulic, control unit, removable as a unit from said propeller, a sleeve, said control unit being rotatably mounted on said sleeve, a hub having a projection adapted to telescope with said sleeve, means securing said sleeve on said projection, and means cooperating with said sleeve and projection forming separate fluid channels connecting said hub and control unit.

9. In a hydraulically actuated propeller having a propeller-carried, separate, removable, hydraulic, control unit, removable as a unit from said propeller, a sleeve, said control unit being rotatably mounted on said sleeve, a hub having a projection adapted to telescope with said sleeve, means securing said sleeve on said projection, and means cooperating with said sleeve and projection forming a hydraulic control connection between said control unit and said hub.

10. In a hydraulic control for a controllable pitch propeller having pitch changing mechanism, a governor valve, a source of fluid pressure, a relief valve for regulating said pressure, means leading pressure fluid to the rear of said relief valve to increase the relief setting thereof, conduits leading from said governor valve to said propeller, one to the pitch increasing, and one to the pitch decreasing side of the pitch changing mechanism, a fluid motor connected with said governor valve, a reversing valve for directing said pressure fluid to said motor to move said valve to direct said pressure fluid to the pitch decreasing side of said pitch changing mechanism to reverse the propeller pitch, a shuttle valve having one end connected with said conduit leading to said pitch increasing side and the other end connected to said motor, said shuttle valve being operable by the predominant pressure thereon to direct said predominant pressure to said means leading to the rear of said relief valve to thereby increase the pressure of said source whenever the propeller pitch is being increased or reversed.

11. In a non-rotating propeller control unit adapted to be assembled with a rotatable propeller and form part of a unitary propeller-control assembly, a reservoir, a sump, a pump for pumping fluid from said sump to said reservoir, a running joint forming a bearing between said non-rotating control unit and said rotatable propeller, fluid passages in said running joint forming a fluid passage from said unit to said pro-- peller, said sump surrounding the ends of said joint to collect any leakage from said joint.

12. In a non-rotating propeller control unit adapted to be assembled with a rotatable propeller and form part of a unitary propellercontrol assembly, a main casing, a reservoir, a pump supported on said casing in said reservoir for maintaining pressure in said reservoir, a second pump supported on said casing in said reservoir for pumping fluid from said reservoir to control mechanism in said control unit, said reservoir being formed by a curved trough removably secured to said casing and enclosing said pumps.

13. In a non-rotating hydraulic propeller control unit adapted to be assembled with a rotatable propeller and form part of a unitary propellercontrol assembly, a non-rotating main casing, control units supported on said casing, and a curved trough separately removably secured to said casing, enclosing said control units and forming with said casing a reservoir for hydraulic fluid for said control units.

14. A non-rotating control unit for controlling the flow of hydraulic fluid to hydraulic pitch changing mechanism of a propeller, comprising a casing, hydraulic control mechanism supported on said casing, a reservoir for hydraulic fluid, a bearin in said casing for rotatably supporting said casing on said propeller, said casing surrounding said bearing and having drainage space at the end of said bearing, said bearing including means for transferring hydraulic fluid from said control mechanism to said propeller, said drainage space arranged to collect leakage from said bearing.

15. A non-rotating unit for controlling the flow of hydraulic fluid to hydraulic pitch changing mechanism of a propeller, comprising a casing, hydraulic control mechanism supported on said casing, a reservoir for hydraulic fluid, a bearing in said casing for rotatably supporting said casing on said propeller, said casing surrounding said bearing and having drainage space at the end of said bearing, said bearing including means for transferring hydraulic fluid from said control mechanism to said propeller, said drainage space arranged to collect leakage from said bearing, a scavenge pump carried by said casing having an inlet connected with said drainage space and an outlet insaid reservoir.

16. A non-rotating control unit for controlling the flow of hydraulic fluid to hydraulic pitch changing mechanism of a propeller, comprising a casing, hydraulic control mechanism supported on said casing, a reservoir for hydraulic fluid, a bearing in said casing for rotatably supporting said casing on said propeller, said casing surrounding said bearing and having drainage space at the end of said bearing, said bearing including means for transferring hydraulic fluid from said control mechanism to said propeller, said drainage space arranged to collect leakage from said bearing, a vent for said drainage space and a pressure regulating valve for said reservoir.

17. A non-rotating control unit for controlling the flow of hydraulic fluid to hydraulic pitch changing mechanism of a propeller, comprising a casing, hydraulic control mechanism supported on said casing, a reservoir for hydraulic fluid, a bearing in said casing for rotatably supporting said casing on said propeller, said casing surrounding said bearing and having drainage space at the end of said bearing, said drainage space having one wall defined by a rotating seal, said bearing including means for transferring hydraulic fluid from said control mechanism to said propeller, said drainage space arranged to collect leakage from said bearing.

18. In a non-rotating control unit for a hydraulically controlled propeller, a non-rotating casing, a reservoir for hydraulic actuating fluid carried by said casing, drainage spaces in said casing for collecting leakage within said casing, a relief valve for said reservoir, an inlet for said relief valve in an air space adjacent the top of said reservoir, a discharge for said relief valve into said drainage space at a point spaced from the top of said drainage space, and a vent for said drainage space adjacent the top of said drainage space, a scavenge pump having an inlet adjacent the bottom of said drainage space and a discharge into said reservoir, whereby the drainage area is emptied of oil, and air is vented from both the reservoir and the drainage area.

JOHN E. ANDERSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,264,089 Martin Nov. 25, 1941 2,352,336 Martin June 27, 1944 2,364,672 Stevenson Dec. 12, 1944 2,403,532 Hoover July 9, 1946 2,476,638 Stuart July 19, 1949 FOREIGN PATENTS Number Country Date 580,923 Great Britain Sept. 25, 1946 629,540 Great Britain Sept. 22, 1949 

